Partisan opponents in the U.S. Senate race escalated their charges Friday as the race continued veering toward the negative some five weeks before Election Day.

Democratic supporters of U.S. Sen. Robert Menendez accused Republicans of engaging in an unabashed campaign of "mudslinging" to avoid discussing serious national issues.

Republican backers of GOP challenger Tom Kean Jr. asked the state Attorney General's Office to investigate the connection between Menendez and a powerful North Jersey attorney, two days after the release of secretly taped conversations that have rocked the campaign.

A lawsuit by Dr. Oscar Sandoval, a Union City psychiatrist, against prominent Democratic lawyer Donald Scarinci and others relies on tapes to bolster his charge that the psychiatrist was the victim of political retribution.

Scarinci, Menendez's longtime friend and political ally, was charged in the suit with dropping Menendez's name to pressure Sandoval to hire a party supporter or else lose his government medical contract.

"For more than 20 years, Bob Menendez and Donald Scarinci have been joined at the hip," Tom Wilson, chairman of the Republican State Committee, said at a State House press conference Friday. "If Menendez didn't know that Donald Scarinci was out making deals and wielding influence using Bob Menendez's name, then he is the only person in New Jersey who didn't."

The issue arose after Sandoval, who is at the center of a Hudson County corruption scandal, released an embarrassing 1999 recording of Scarinci. In transcripts of the tape, Scarinci invokes Menendez's name while urging Sandoval to split his government contract with another physician.

Sandoval's lawsuit against Scarinci and others relies on this and other tapes to bolster his charge that the psychiatrist was the victim of political retribution when his contract with Hudson County eventually was canceled.

This week, the Menendez campaign distanced itself from Scarinci, saying he will no longer play a role in the senator's campaign. The Lyndhurst-based lawyer has been a major fund-raiser and political confidant for the senator, a Hudson County Democrat.

Partisan backers of Menendez shot back on Friday, saying Kean was relying on an unsavory convict to dodge serious debate on important policy matters. Several years ago, Sandoval paid bribes to the former Hudson County executive, only later to become chief witness for federal prosecutors at a trial where the official was convicted on corruption charges.

"This is just the latest chapter from a campaign that is stuck in the gutter and is determined to stay there," Joe Cryan, chairman of the state Democratic Party, said in a statement. "Tom Kean Jr. can't defend his pro-Bush, pro-war positions to the people of New Jersey, so he is relying on the Republican game plan of personal attacks and political smears."

David Wald, a spokesman for the state Attorney General's Office, declined to comment on Wilson's call for the agency to investigate dealings between Scarinci and Menendez.

Scarinci was unavailable for comment Friday. In a previous statement, he said his discussions with Sandoval were not sanctioned by Menendez, insisting he could not comment more broadly because of the pending lawsuit.

Kean and Menendez are statistically tied in most polls in a race the voters will decide on Nov. 7.